KR100441159B1 - Release film - Google Patents

Abstract

The present invention includes a base film, and a primer layer and a release layer formed sequentially on the base film, wherein the primer layer comprises a water-soluble polyurethane, a silane coupling agent and a filler of the formula (1), and the mixed weight ratio thereof is 25 to It is related with the release film characterized by being 75: 25-75: 1-30. The release film according to the present invention is applicable irrespective of the components of the release layer, and maintains excellent adhesive force almost intact even when used for a long time in a poor environment as well as initial adhesion. Therefore, a satisfactory effect can be obtained even if it is used for any purpose such as a label, a tape, a stamping foil, or a cosmetic transfer paper.

Description

Release film {Release film}

The present invention relates to a release film, and more particularly, to a release film further comprising a primer layer for improving the adhesion between the base film and the release layer.

A release film is an adhesive surface formed on at least one surface thereof, such as a label, a tape, a stamping foil, a toilet paper transfer paper, and the like, and can be used as a support for a release material. A release film is usually formed on a base film (paper or polymer film), and on the base film. It includes a release layer formed by applying a composition for forming a release layer, preferably a composition for forming a release layer containing silicon, followed by drying and thermosetting.

However, since the paper or polymer film used as the base film in the release film is not reactive or less reactive, the adhesion to the release layer formed thereon is very weak and the adhesion decreases over time, causing the release layer to fall off. Can be. In addition, release of the release material may occur together with the release layer, and the adhesion to the adherend may also be greatly reduced.

In order to overcome this problem, a method of improving the adhesion of the release layer has been proposed by adding an adhesion enhancer when forming the release layer. However, this is not preferable in that it does not provide satisfactory adhesion.

On the other hand, there is another method for forming a primer layer between the base film and the release layer.

The primer layer is widely used in the field of packaging industry, magnetic tape, printing photo industry, and the like. For example, polyester copolymerized with isophthalate, alkylene glycol, and sulfur monomer for the purpose of improving adhesion to the metal deposition layer is used. A method of forming a primer layer using is disclosed in US Pat. No. 4,493,872. As another example, a method of forming a primer layer of a photographic serving film using a mixture of polyester, aziridine and gelatin has been disclosed in US Pat. No. 4,181,528.

In addition, such a primer layer may be introduce | transduced into the release film which is the field of this invention.

As an example, Japanese Patent Application Laid-Open No. Hei 64-5838 discloses an example in which a primer layer including a silane coupling agent capable of a curing reaction by an epoxy group, an amino group, a vinyl group, a mercapto group, or the like is formed between a polyester film and a silicone release layer. US Patent No. 5,212,260 discloses an example in which a primer layer comprising a polyester copolymer and a glycidylsilane coupling agent is formed between a polyester film and a silicone release layer.

However, the above-mentioned primer layers do not exhibit satisfactory adhesion improvement effect, and the silicone included in the release layer is various, such as a solvent type, a solventless type, an emulsion type, or a UV curable type, depending on the manufacturing process, and the curing catalyst according to the type of the base film. Since these are different, there are various problems in applying them universally.

The technical problem to be achieved by the present invention is to provide a release film comprising a primer layer that can be applied universally regardless of the components of the base film and the release layer and improve the adhesion between the base film and the release layer.

Technical problem of the present invention includes a base film, and a primer layer and a release layer sequentially formed on the base film, wherein the primer layer comprises a water-soluble polyurethane, a silane coupling agent of Formula 1, a filler and a mixed weight ratio thereof It can be made by a release film, characterized in that 25 to 75:25 to 75: 1 to 30.

XY-Si-R ₁ R ₂ R ₃

(Wherein X is a glycidyl or vinyl group, Y is a linear or branched substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, R ₁ , R ₂ and R ₃ may be the same or different and are hydrolyzable, respectively) Or a C 1-5 alkoxy group which is non-hydrolyzable).

In the present invention, any kind of polymer film that can be used as the base film may be used as long as it is used in the field of the present invention, and examples thereof include polyester-based films such as polyethylene terephthalate and polybutylene terephthalate. And polyamide film such as nylon, polyolefin film such as polyethylene or polypropylene, polysulfone film, polycarbonate film, cellulose trivinylacetate film and the like.

In the primer layer, on the other hand, the water-soluble polyurethane is a thermosetting resin, and a polyisocyanate is reacted with a polyester polyol containing an active hydrogen atom exhibiting reactivity with an isocyanate group to form a urethane resin precursor, and the precursor is sodium bisulfite or potassium bisulfite. And reacted with at least one bisulfite selected from ammonium bisulfite and the like to block and then disperse with water. At this time, the polyester polyol is saturated or unsaturated dicarboxylic acid, such as succinic acid, adipic acid, sebacic acid, maleic acid phthalic acid, and the like and ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, neopentyl glycol and hexylene glycol It is prepared by polycondensing alkylene glycols such as and the like. On the other hand, examples of the polyisocyanate are 2,4- or 2,6-tolylene diisocyanate, xylene diisocyanate, 4,4-diphenylmethane diisocyanate, tetramethylene diisocyanate, hexamethyl diisocyanate, trimethylhexamethylene diisocyanate And aliphatic diisocyanate.

In addition, the silane coupling agent is usually water-soluble and excellent in dispersibility, and may be preferably used in the form of a mixture containing glycidylpropylsilane and vinylpropylsilane in a weight ratio of 25 to 75:75 to 25.

Finally, the filler is a silica-based or alumina-based water dispersible inorganic filler, and its size and surface area are preferably 100 nm or less and 1,000 cm 2 or less, respectively.

When the size of the filler is more than 100nm or more than 1,000cm 2, respectively, the effects of other additives of the primer layer are not exerted, which is not preferable.

The release film according to the present invention may be prepared according to a method commonly used in the field of the present invention, the manufacturing method according to one embodiment thereof is as follows:

First, a bisulfite salt of an alcohol or an alkali metal or an earth metal in a urethane resin precursor or a mixture thereof, prepared by reacting a polyester polyol which is a condensation polymer of an unsaturated dicarboxylic acid with an alkylene glycol, and a polyisocyanate (for example, sodium bisulfite) Is added and mixed under stirring. This mixture is diluted with water to produce a blocked water soluble polyurethane.

The water-soluble polyurethane thus prepared is mixed with a silane coupling agent and a filler to prepare an aqueous dispersion for forming a primer layer.

Subsequently, the polyester resin having an intrinsic viscosity of 0.4 to 0.9 dl / g is melt-extruded using a conventional method, and then electrostatically applied to a cooling roll at 20 to 30 ° C. to form a sheet, and the unstretched sheet is 70 to Stretching is performed 2 to 5 times, preferably 3 to 4 times in the longitudinal direction at 100 캜, and then stretched 2 to 5 times, preferably 3 to 4 times in the transverse direction at 100 to 120 캜. The biaxially stretched polyester film is then prepared by heat-setting the biaxially stretched sheet at 200 to 260 캜, preferably 220 to 240 캜 to dry the aqueous dispersion on the sheet surface. In this case, the aqueous dispersion may be coated on at least one surface of the unstretched or uniaxially stretched polyester sheet or the biaxially stretched polyester film to form a primer layer. A release film is obtained by forming a release layer containing silicone on the formed primer layer.

In the production method of such a release film, the aqueous dispersion for forming a primer layer may be coated on at least one surface of the uniaxially stretched polyester film stretched only in one direction in the transverse or longitudinal direction, the preferred coating amount is 0.01 ~ 0.5g / ㎡ to be. On the other hand, the coating method may be any method that can be commonly used in the field of the present invention, but preferably, a roll coating method using gravure roll, reverse gravure roll, bar coating method using air, etc. The coating method using a knife etc. can be used.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

First, the adhesion evaluation method for the release film obtained in the following Examples and Comparative Examples is as follows.

<Adhesion evaluation>

The release film was left at room temperature (25 ° C.) for 3 days, 10 days and 30 days, respectively, and in water at 40 ° C. for 1 day, 3 days, 7 days and 10 days, respectively, and then pushed the release layer very strongly with fingers. Observe that the release layer is eliminated.

The test is repeated 10 times to determine the grade according to the following evaluation criteria.

0: when dropping off the first time

1: If you drop out the second or third time

2: If you drop out the fourth to sixth

3: in the 7th to 8th rounds

4: If you drop out the 9th to 10th

5: If you do not drop out after 10 runs

Examples 1-4 and Comparative Examples 1-5

First, a water soluble polyurethane was prepared according to the following method:

80 g of ethanol was diluted in 50 g of a urethane resin precursor (4.5% of free isocyanate group) obtained by reacting hexamethylene diisocyanate with polyester diol (molecular weight: 2,000) of butylene glycol adipic acid, and 56 g of 20% sodium bisulfite was diluted. Put and mix under stirring at 35-45 ° C for 60 minutes. The mixture was diluted with water to give 500 g of an aqueous solution of blocked urethane resin precursor (concentration: 20%).

The water-soluble polyurethane thus obtained was mixed with a silane coupling agent such as vinylsilane or glycidylpropylsilane and a filler (SiO _x ) in a mixing ratio shown in Table 1 below to prepare an aqueous dispersion for forming a primer layer.

Next, the aqueous dispersion for forming the primer layer obtained by using a Meyer bar is applied onto a polyethylene terephthalate film (SH71, SKC Co., Ltd.) of 100㎛ thickness, then dried at 180 ℃ for 2 minutes The primer layer which is 0.5 micrometer was formed.

Subsequently, by applying a release layer-forming composition containing a solvent-free silicone (syl-off 7673, Dow Corning Co., Ltd.) on the primer layer using a Mayer bar, and then cured at 120 ℃ for 30 seconds to form a release layer Release Film A was prepared.

On the other hand, except using a composition for forming a release layer containing a solvent-type silicone (KS-774, ShinEtsut Co., Ltd.) and forming a release layer at a curing temperature and time of 150 ℃ and 1 minute, respectively, According to the same method, release film B was prepared.

According to the evaluation method, the adhesion of the release films A and B was evaluated and the results are shown in Tables 2 and 3, respectively.

Primer layer Furtherance Concentration (% by weight) Water soluble polyurethane Silane coupling agent Filler Example One One 2 One 2 2 6 2 One 2 3 One One One 2 4 One One One 4 Comparative example One - - - - 2 One - - 2 3 - One One 2 4 - One - 2 5 WR-901 (Japanese synthetic chemical product) 2

Early After standing at room temperature After underwater 3 days later 10 days later 30 days later 1 day later 3 days later 7 days later 10 days later Example One 5 4 5 5 5 5 5 5 2 5 5 4 5 5 5 5 4 3 5 5 5 5 4 5 4 4 4 5 4 5 4 5 5 5 5 Comparative example One 5 3 One 0 One 0 0 0 2 5 3 One One 4 2 2 0 3 4 3 3 One One One 0 0 4 4 3 0 0 2 One One 0 5 5 2 One One 0 0 0 0

Early After standing at room temperature After underwater 3 days later 10 days later 30 days later 1 day later 3 days later 7 days later 10 days later Example One 5 5 5 4 5 5 5 5 2 5 5 4 4 4 4 4 4 3 5 5 5 5 5 4 4 5 4 5 4 4 4 4 3 4 4 Comparative example One 5 3 2 2 One 0 0 0 2 4 4 3 One 3 3 One 0 3 5 4 One 0 0 0 One 0 4 5 3 3 3 2 One 2 2 5 4 3 0 0 One One 0 0

As can be seen from the results of Table 1, in the case of the release film according to the present invention (release films A and B prepared according to Examples 1 to 4) not only excellent initial adhesive force but also 30 days at room temperature, in water It has been shown to maintain good adhesion even after being left for 10 days or more. Moreover, it turns out that even if it uses either a solvent type or a non-solvent type silicone as a mold release layer, it shows the substantially similar adhesiveness and adhesive force retention.

On the contrary, in the case of not including the primer layer according to the present invention or including the conventional primer layer (relative films A and B prepared according to Comparative Examples 1 to 5), the initial adhesive strength is somewhat lower than that of the release film according to the present invention. Not only is it weak, it can be seen that a longer deterioration period causes a significant decrease in adhesion.

The release film according to the present invention is applicable irrespective of the components of the release layer, and maintains excellent adhesive force almost intact even when used for a long time in a poor environment as well as initial adhesion. Therefore, a satisfactory effect can be obtained even if it is used for any purpose such as a label, a tape, a stamping foil, or a cosmetic transfer paper.

Claims (8)

A base film, and a primer layer and a release layer sequentially formed on the base film, The primer layer comprises a water-soluble polyurethane, a silane coupling agent and a filler of the following formula (1) and a mixing weight ratio of 25 to 75:25 to 75: 1 to 30, characterized in that the release film. <Formula 1> XY-Si-R ₁ R ₂ R ₃ (Wherein X is a glycidyl or vinyl group, Y is a linear or branched substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, R ₁ , R ₂ and R ₃ may be the same or different and are hydrolyzable, respectively) Or a C 1-5 alkoxy group which is non-hydrolyzable). The release film of claim 1, wherein the base film is at least one selected from the group consisting of polyester, polyolefin, polyimide, polysulfone, polycarbonate, and cellulose trivinylacetate. The method of claim 1, wherein the water-soluble polyurethane is prepared by condensation polymerization of saturated or unsaturated dicarboxylic acid with alkylene glycol having 2 to 8 carbon atoms, and reacting a polyester polyol containing an active hydrogen atom with polyisocyanate to form a precursor. And reacting this precursor with bisulfite salts of alkali or alkaline earth metals. 4. The release film of claim 3, wherein the dicarboxylic acid is selected from the group consisting of succinic acid, adipic acid, sebacic acid, phthalic acid and maleic acid. The release film of claim 3, wherein the alkylene glycol is selected from the group consisting of ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, and hexylene glycol. The polyisocyanate of claim 3, wherein the polyisocyanate is 2,4- or 2,6-tolylene diisocyanate, xylene diisocyanate, 4,4-diphenylmethane diisocyanate, tetramethylene diisocyanate, hexamethyl diisocyanate, trimethylhexamethylene Release film, characterized in that selected from the group consisting of diisocyanate and aliphatic diisocyanate. The release film according to claim 1, wherein the silane coupling agent is a mixture containing glycidylpropylsilane and vinylpropylsilane in a weight ratio of 25 to 75:75 to 25. The release film according to claim 1, wherein the filler is a silica-based or alumina-based water dispersible filler and its size and surface area are 100 nm or less and 1,000 cm 2 or less, respectively.